Lifting tongs



Jan. 2, 1951 M. R. HEPPENSTALL LIFTING'TONGS Filed Sept. 9,- 1949 2Sheets-Sheet 1 NVENTOR.

Jan. 2, 1951 M. R. HEPPENSTALL Filed Se t. 9, 1949 2 Sheets-Sheet 2INVENTOR.

Patented Jan. 2, 1951 UNITED S TATES assess TENT OFFHCE LIFTING TONGSApplication September 9, 1949, Serial No. 114,761

8 Claims. '1

This invention relates to lifting tongs of the type commonly used tolift and transfer material, such as coils of steel strip, ingots, etc.,from .place to place in a'mill.

Tongs of this type generally include a, pair of load-grappling,shoe-bearing arms carried by a toggle, o the "like, the arrangementbeing such that, when the 'toggleis lifted, the shoes move towards eachother to grip andlift the load and, when the load is deposited, theshoes spread apart to release it. .To hold the arms in such a spreadposition, a number of tongs are provided with latching mechanism, suchas the mechanism disclosed in my United States Patent 1,839,389, thatlocks the gripper arms open and permits the tongs to belifted free ofthe load, and in addition, holds the arms in their spreadapart positionas the tongs are'lowered into a load-gripping position.

A number of these tongs, however, are not as satisfactory as could bedesired either due to structural weaknesses which result in breakage,

or because, under certain conditions, they grip the load imperfectly. Toassure a solid, secure gripping of the load by the .shoes of the tones,itis desirable to mountthe shoe arms in such .a way that any lifting.force on the tongs, whether it is vertically upward or at an angle tothe vertical, exerts an equal force on both of the shoe arms and, thus,coordinates the movement of the arms toward each other intoload-gripping position. Althoughsuch co-ordinated movement has beenattempted, nevertheless the mechanism used for eflecting it has not beensuffic-iently strong to sustain any substantial load. Consequently,considerable breakage results, such breakage bein particularly frequentin tongs which also include the arm latching feature described above.

It is among the objects of the present invention to provide liftingtongs in which the movement of the shoe armsis co-ordinated to assure asecure gripping of the load to be lifted, and, :also, in which suchco-ordinationis efiected by means capable of sustaining heavy loads.

Further objects are to simplify and strengthen the construction of tongshaving such co-ordinated movement and to include in the constructionlatching means for holding the shoe-arms in a spread-apart position.

Although a full description of the invention will be given, itssubstance resides in forming the structural members into a pair ofparallelograms which are connected together by a strong link, thelinkagecausing the legs of the parallelograms to move in unison. Thelower leg of each parallelogram carries a shoe member for gripping theload to be lifted, and each of these lower legs is pivotally suspendedfrom a toggle which, when engaged and lifted by a crane, or the like,causes the lower legs to move towards each other. rection of the pull ofthe crane on the toggle, the force tending to move each lower leg issubstantially equal because of the linkage connectlllg the twoparallelogram's of which each is a part.

The preferred embodiment of'the invention is illustrated in theaccompanying drawings of which Fig. 1 is a side elevation of the tongsshowing their grappling arms in a spread or open position; Fig. 2 is aview similar to Fig. 1 showing the arms in a closed, grappling position;Fig. 3 a left-hand end view of the tongs as shown in Fig, 2; Figs. 4, 5and 6 sections taken on line IV-IV, VV and VI-VI, respectively, of Fig.2; and Figs. '7 and 8 rather diagrammatic side elevationsthese two viewstaken together being analogous to a single exploded view of Fig. 1 inthat each view shows one of the grappling arms and the functionalmembers for supporting and moving it.

Referring to the drawings, the tongs illustrated are formed,particularly, for gripping and transporting coils of steel strip, suchas coil I, the coil gripping members being shoes 2 and 3 each carried byseparate grappling arms 3 and 6. Arm 6, as shown in Fig. 3, is formed ofa pair of horizontally extending angle members 7 and 8 to the bottomsurface of both of which is integrally secured shoe 3. Further, shoe 3is positioned toward the center of arm 6 and the bottoms of the angleslie in a horizontal plane to provide a level surface on which the tongsrest when set on a coil as shown in Figs. 1 and 2. Arm 4, on the otherhand, is a relatively wide bar slidably fitted between the two angles ofarm 6, the left-hand end portion of arm 4 (Figs. 1 and 2) being bentdownwardly and loosely carrying, on pin 9, shoe member 2.

Both of the shoe-carrying arms are pivotally carried and moved by atoggle I l which has pairs of lower and upper links l2, l3, and l4, l5,respectively, the upper links being hung at a central point on a king.pin l6 that also mounts a bail, or clevis, l? by which the tongs arelifted. In the preferred structure '(Fig. 3), each pair of toggle linksincludes spaced front and rear members, these being 12a, lZb, I311, I31)and Ma, Mb, 55a, l5b. The pivotal connection between the Thus,regardless of the di-- lower toggle links and the shoe-carrying arms areon pins l8 and 19, pin it (Figs. 4 and 7) extending through left-handarm Q and being pivotaliy supported in the front and rear members [2a,l2?) of lower link l2; while pin l9 (Figs. 6 and 8) extends throughangle 1 and 8 of arm 6 and is mounted in members l3a, 317 of lower linkis, these links E311, i3!) being disposed adjacent to and exteriorly ofangles 1 and 8.

Further, lower links l2 and i3 are pivotaliy connected at points abovepins i8 and E9 to another horizontal bar 2!. Bar 2i, also, is formed ofspaced front and rear bar members 25a, 2 lb that extend adjacent to thefront and rear members of lower links l2 and I3 of the toggle, these barmembers being disposed exteriorly of link 22 at their left-hand ends(Fig. 3), and interiorly of link H3 at their right-hand ends (Fig. 6).The connections of links l2 and it to bar members 21a and Zlb are madeby pins 22, 23, pin 22 (Fig. 4) being mounted at its ends in the frontand rear members of horizontal bar 29 and extending transversely throughfront and rear members !2a, [2b of link l2. Similarly, at the right-handend of the tongs, pin 23 (Fig. 6) is carried at its ends in the frontand rear members of bar 2i and extends through front and rear membersl3a, 13b of link 13.

With the connections described so far, it will be apparent that anyupward movement of the toggle by a pull exerted on bail ll would act topivot lower links 52 and it on their pins 22 and Z3, and, since theouter ends of these links are connected to arms 5 and 6, also, wouldmove these arms toward each other. 23 act as fulcrum points, about whichlinks l2 and I3 pivot, to produce the arm movement. It will beappreciated, however, that links l2 and it support only the outer endsof arms 4 and 6. To support the inner ends of each of these arms, short,vertically-inc ined links 2% and 2? are provided, link 26 being formedof front and rear members 25a, 26b (Fig. 5) that, at their lower ends,bracket the inner end of arm A and are pivotally connected thereto by atransverse pivot pin 28. Near their upper ends link members 26a, 26bextend interiorly of and adjacent to bar members 21a, 2H), and arepivoted to these bar members on another pivot pin 29.

Link 2'5, which supports the left-hand end of shoe-carrying arm 6, alsois formed of front and rear link members Zla, 272) (Fig. 3), thesemembers extending at their upper ends adjacent to and outwardly of bar 2l, and, at their lower ends adjacent to and outwardly of angles 7 and 8of arm 6. Further, at its upper end, link 2?! is mounted on pin 22 toform a pivotal connection between link 2? and bar 2!. At its lower end,link 2! is pivotaly connected to arm 6 by means of short studs 32a,322).

From the above, it now should be noted that the outer and inner ends ofboth horizontal arms are connected to horizontal bar 2! in such a mannerthat a pair of parallelograms are formed, these para lelograms beingindicated by the dot and dash lines of Figs. '7 and 8. As there seen,the left-hand parallelogram (Fig. '7) is formed of arm 4, bar 2i, link28 and the portion of toggle link 52 that lies between fulcrum pin 22and pin l3, this portion being designated by the letter A. Similarly,the right-hand parallelogram (Fig. 8) is formed of arm 6, bar 25, link2! and a portion B of link 53. Of course, to form parallelograms it isnecessary that the opposite legs be In effect, pins 22 andparallelograms.

. the assembled tongs.

disposing all of the upper as well as the lower, pivotal axes of themembers of both parallelograms on the same horizontal planes.

Consequently, when there is a direct upward pull on the parallelograms,exerted by a pull on bail ll, the lower legs of the parallelograms,which are arms 4 and 5, move toward each other in horizontal directionsand, eventually, close upon a coil placed between them. The importantthing, however, is that, as can be noted most clearly in Figs. '7 and 8,each parallelogram can be swun by itself, and the swinging of either onewould not necessarily cause movement of the other. Therefore, even whenthe elements of Figs. '7 and 8 are combined to form tongs, the result,nevertheless, is that the parallelograms can swing independently. As aresult, although arms 4 and S would move in horizontal planes, there isno guarantee that they would move together in the same horizontal plane.By way of example, if the lifting force were at an angle to thevertical, as most often is the case when a crane is used, more forcewould be exerted on one arm to move it than on the other and,consequently, more movement would be produced in that one arm than inthe other. Therefore, at the instant in which the shoes gripped thecoil, the effective gripping force of one shoe would be applied to thecoil above or below the effective gripping force of the other shoe. Suchwould result in an insecure, and unsafe grip and, also, in a grip thatwould tend to tilt the coil as it is raised into mid-air.

To prevent such insecure gripping, the tongs of the present inventionare provided with means to cause an equal, horizontally-directed forceto be applied to each shoe-arm, regardless of the direction of the pullof the crane upon the tongs, the particular means employed being afreely-swing ing connecting link 36 that ties together the twoPreferably (Figs. '7 and 8), link 36 ties vertically-inclined link, orleg, 25 of the left-hand parallelogram to portion, or leg, B of theright-hand parallelogram, it being apparent that these two legs lierather closely together in However, other parallelogram legs could betied together to accomplish the desired action and, also, the particulararrangement of link members used to achieve the tie possibly could beaccomplished in other ways than that to be described.

In the particular arrangement shown, link 25 is specially formed tofacilitate its connection by being provided with outwardly projectingportion 3? (Figs. 1 and 2). Also, portion B, which is the portion oflower toggle link l3 lying between pivot pins 23 and i9 is adapted to beinterconnected by mounting a somewhat triangular link 38 on pins 23 andi9, this link having identically shaped front and rear members 380: and382) (Fig. 6)

; disposed in a spaced relation between the front and rear members ofbar 2 5. Also, triangular link 38 has a portion projecting towardportion 3? of link 26, this portion, as well as portion 3'l beingprovided with openings which receive pins 3! and 32 on which connectinglink 36 is mounted.

With the two parallelograms so tied together, it should now be notedthat any force tending to move, or swing, either one of them would betranslated through link 35 to the other to exert a substantially equalmoving force on the other. For example, should the tongs be lifted inthe direction of arrow C, Fig. 1, instead of in a vertical direction,more force might be exerted on arm 6 than on arm 4, but, since anymovement equal and parallel and this is accomplished by 75 of arm 6produces an opposite movement of essence arm 4, the forces tending tomove the arms to-'- gether are equalized. The result is that the armstend to: move equal distances: toward each other to grip the loads-sothat, when the load is gripped, the effective gripping 'force of botharms isdirected in the same horizontal plane. Stated in .another way, nomatter in which direction the load lifting force is applied,vertically-inclined links. 26 and '2!- swing through :the same arcs tomaintain the arms in the same horizontal plane throughout theirmovement.

As mentioned above, the invention also contemplates the use of latchingmechanism-to hold the shoe-arms in a spread-apart position, both .tofree the .tongs from the load and to allow two-part mechanism, one partbeing .a keeper member 46 (Fig. 1) carried at the right-hand end of bar2|, and the othera sleeve 41, mounted on toggle link l2 of the tongs,the-sleeve mounting a vertically reciprocable and rotatable plunger 4%provided with an enlarged head portion. In operation, after the tongshave gripped and transported a load, and, when they have been lowered todeposit theload at the desired location, the toggles collapse causingplunger 48 to enter keeper member 46. However astheplunger enters thekeeper member, certain cams (not shown) formed interiorly of sleeve 47!,efi'ecta rotation of the plunger which looks the members together.Consequently, the tongs can be lifted clear of the deposited load andmoved on to pick up another load. To pick up the new load, the tongs,with their shoe-arms-spread and locked apart, are lowered onto the load,but, in settling on the load, plunger 48 again .is rotated so as topermit it to withdraw from the keeper when the tongs again are lifted.Consequently, the tongs can move together upon the next lift, to gripthe load.

In the present tones, the tying together of the parallelograms assiststhe latching mechanism in that it assures that both shoe-arms will berigidly locked in their spread-apart position. The need for locking botharms can be more readil appreciated if .it be assumed that theparallelograms were not tied together by link 36, since, if such werethe case, only arm 4 would be locked, while arm 6 and toggle link Itwould be relatively free to "swing. Such freeswinging of arm 6 woulddefeat the purpose of the latch, particularly when it is desired tolower the tongs onto a new load with their shoe-arms spread apart,since, in that event, arm 6 could swing inwardly to such a position thatits shoe would not fit around the load. However, when arms 4 and 6 aretied together by link 36, the locking-down of arm 4 also locks arm 6 sothat both arms are rigidly held apart.

A further advantage of tying the two arms together by link 36 is thatthe link can be made sufiiciently strong to support a substantialportion of the load for which the tong is designed. In this regard, itsometimes happens that considerable load is placed upon link 36,particularly, when the tongs are being lifted free of a de posited loadwith their shoe-arms locked apart.

Inisuch case,.i' the. coil is nearly as. wide as. the.

space between the fully spread-apartshoes, the shoes may catch on thecoil, thereby causing the weight of the coilitobe borne. by the tongsand, particularly, by link 35. However, by using a sufficiently heavyand strong link, the possibility of breakageis practically avoided.

.Erom the above description it is believed that themanner in which thetongs pick up, transportand deposit theirloads should beclear,particularly, since the 'generaloperation of these tongs is similar tomany others now in use. However, the present tongs: have a. number ofadvantages over the others since they assure a perfect gripping of theload .as well as improve the arm locking-mechanism. Further, thestructural arrangement is such thatthe tongs. can be manufacturedeconomically from :a few parts and, nevertheless, be unusually strongand safe to use.

According, to the provisions of the patent statutes, I have explainedthe principle, preferred embodiment and mode of operation'of myinvention, and have illustrated and described what I now consider torepresent its best-embodiment. However, I desire to have it understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically illustrated and described.

I claim:

'l. Lifting tongs comprising .a pair of grappling arms each having ahorizontal section, a horizontal bar disposed above said arms, apair ofload-supporting tog le links each connected to enact said armsformovingthe arms toward and away from each othena pair of parallel verticallyinclined links pivotally connecting each of said arms to said. bar, oneof said vertically inclined links of each of said pairs being formed bythe lower ends of said tog le links and said bar and arm-connectinglinks forming with said bar and arms a pair of parallelograms, and alink connecting together said parallelograms for effecting simultaneousmovement of said grappling arms.

2. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links having lower memberspivotally connected at their lower ends one to each of said arms, ahorizontally disposed bar extending above said arms and pivotallyconnected at-spaceo points to each of said lower toggle links, two tielinks eaoh'pivotally connected at its upper end to said bar andpivotally connected at their lower ends one to each .of said said armsparallel legs of a parallelogram whose other parallel legs areone ofsaid, tie links and the lower portion of the lower member of one of saidtoggle links, and a link connecting together said parallelograms foreliecting simultaneous movement of said grappling arms.

3. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links having lower memberspivotally connected at their lower ends one to each of said arms, ahorizontally disposed bar extending above said arms and pivotallyconnected at spaced points to each of said lower toggle links, two tielinks each pivotally connected at its upper end to said bar andpivotally connected at their lower ends one to each of said grapplingarms, the pivotal axes of said toggle links and said tie links beingdisposed in the same horizontal plane both in said bar and grapplingarms whereby said arms, bar, toggle and tie links form a pair ofparallelograms, and a freelyswinging link connecting said parallelogramfor effecting simultaneous movement of said grappling arms.

v4. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links having lower memberspivotally connected at their lower ends one to each of said arms, ahorizontally disposed bar extending above said arms and pivotallyconnected at spaced points to each of said lower toggle links, two tielinks each pivotally connected at its upper end to said bar andpivotally connected at their lower ends one to each of said grapplingarms, said bar forming with each of said arms parallel legs of aparallelogram whose other parallel legs are one of said tie links andthe lower portion of the lower member of one of said toggle links, afreely-swinging link connecting together said parallelograms foreffecting simultaneous movement of said grappling arms, and latchingmechanism for locking said arms in a spread-apart position.

5. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links havingpivotally-connected upper and lower members said lower members beingpivotally connected at their lower ends one to each of said arms, ahorizontally disposed bar extending above said arms and pivotallyconnected at spaced points to each of said lower toggle links, two tielinks each pivotally connected at its upper end to said bar andpivotally connected at their lower ends one to each of said grapplingarms, said bar forming with each of said arms parallel legs of aparallelogram whose other parallel legs are one of said tie links andthe lower portion of the lower member of one of said toggle links, afreely-swinging link connecting together said parallelograms foreffecting simultaneous movement of said grappling arms, and two-partlatching mechanism for locking one of said grappling arms in aspreadapart condition, one of said partsbeing carried by said bar andthe other by the toggle link member connected to said one arm.

6. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links having lower memberspivotally connected at their lower ends one to the outer end of each ofsaid arms, a horizontally d sposed bar extending above said arms andpivotally connected at spaced points to each of said lower toggle links,two tie links each pivotally connected at its upper end to said bar andpivotally connected at their lower ends to the inner end of each of saidgrappling arm, said bar forming with each' of said a'rms'parallel legsof a parallelogram whose other parallel legs are one of said tie linksand the lower portion of the lower member of one of said toggle links,and a freelyswinging link connecting together the tie link of oneparallelogram with said toggle link lower portion of the otherparallelogram for efiecting simultaneous movement of said grapplingarms, said swinging link-connected members being disposed close to oneanother and having projecting portions fo mounting said link.

'7. Lifting tongs comprising a pair of grappling arms each having ahorizontal section, loadsupporting toggle links having the lower memberpivotally connected at their lower ends one to the outer end of each ofsaid arms, a horizontally disposed bar extending above said arms andpivotally connected at spaced points to each of said lowe toggle links,two tie links each pivotally connected at its upper end to said bar andpivotally connected at their lower ends to the inner end of each of saidgrappling arm, said bar forming with each of said arms parallel legs ofa parallelogram whose other parallel legs are one of said tie links andthe lower portion of the lower member of one of said toggle links, afreelyswinging link connecting together the tie link of oneparallelogram with said toggle link lower portions of the otherparallelogram for eiiecting simultaneous movement of said grapplingarms, said swinging link-connected members being disposed close to oneanother and having projecting portions for mounting said link, andlatching mechanism for locking said arms in a spreadapart position.

8. Coil lifting tongs comprising a pair of shoebearing grappling membershaving horizontal sections, a horizontal bar disposed above said arms, apair of toggle links each connected to one of said arms for swinging thearms toward and away from each other to grip and release said coil, apair of parallel vertically-inclined links pivotally connecting each ofsaid arms to said bar, one of said vertically-inclined links of each ofsaid pairs being formed by the lower ends of said toggle links and saidbar and arm-connecting links forming with said bar and arms a pair ofparallelograms, and a freely-swinging link connecting together saidparallelograms for effecting simultaneous movement of said shoebearingarms, one of said arms having a horizontal bottom surface adapted torest squarely on the top of said coil as said arms are moved into andout of coil-grappling positions.

MAX R. HEPPENSTAIJJ.

No references cited.

